The B Major 7th chord is a four-note chord made up of B, D♯, F♯, and A♯. It is built from a root, major third, perfect fifth, and major seventh.
Construction
| Note | Interval | Degree |
|---|---|---|
| B | Root | 1 |
| D♯ | Major 3rd | 3 |
| F♯ | Perfect 5th | 5 |
| A♯ | Major 7th | 7 |
B Major 7th Inversions



| Position | Notes |
|---|---|
| Root Position | B – D♯ – F♯ – A♯ |
| 1st Inversion | D♯ – F♯ – A♯ – B |
| 2nd Inversion | F♯ – A♯ – B – D♯ |
| 3rd Inversion | A♯ – B – D♯ – F♯ |
Key Signature
A chord has no key signature of its own, but the B Major 7th is the tonic (I) chord of B Major, whose key signature has 5 sharps (F♯, C♯, G♯, D♯, A♯).
Order of sharps
Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of B Major
These are the triads built on each degree of the B major scale:
How B Major 7th functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where B Major 7th sits diatonically across the common keys:
- In B major, B Major 7th is the I chord — the tonic.
- In D♯ minor, B Major 7th is the VI chord — the tonic.
- In F♯ major, B Major 7th is the IV chord — a predominant.
- In G♯ minor, B Major 7th is the III chord — a mediant / color chord.